Effect of xanthine oxidase-generated extracellular superoxide on skeletal muscle force generation.
Am J Physiol Regul Integr Comp Physiol
; 298(1): R2-8, 2010 Jan.
Article
in En
| MEDLINE
| ID: mdl-19828843
ABSTRACT
Skeletal muscle contractions increase superoxide anion in skeletal muscle extracellular space. We tested the hypotheses that 1) after an isometric contraction protocol, xanthine oxidase (XO) activity is a source of superoxide anion in the extracellular space of skeletal muscle and 2) the increase in XO-derived extracellular superoxide anion during contractions affects skeletal muscle contractile function. Superoxide anion was monitored in the extracellular space of mouse gastrocnemius muscles by following the reduction of cytochrome c in muscle microdialysates. A 15-min protocol of nondamaging isometric contractions increased the reduction of cytochrome c in microdialysates, indicating an increase in superoxide anion. Mice treated with the XO inhibitor oxypurinol showed a smaller increase in superoxide anions in muscle microdialysates following contractions than in microdialysates from muscles of vehicle-treated mice. Intact extensor digitorum longus (EDL) and soleus muscles from mice were also incubated in vitro with oxypurinol or polyethylene glycol-tagged Cu,Zn-SOD. Oxypurinol decreased the maximum tetanic force produced by EDL and soleus muscles, and polyethylene glycol-tagged Cu,Zn-SOD decreased the maximum force production by the EDL muscles. Neither agent influenced the rate of decline in force production when EDL or soleus muscles were repeatedly electrically stimulated using a 5-min fatiguing protocol (stimulation at 40 Hz for 0.1 s every 5 s). Thus these studies indicate that XO activity contributes to the increased superoxide anion detected within the extracellular space of skeletal muscles during nondamaging contractile activity and that XO-derived superoxide anion or derivatives of this radical have a positive effect on muscle force generation during isometric contractions of mouse skeletal muscles.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Xanthine Oxidase
/
Superoxides
/
Muscle, Skeletal
/
Extracellular Space
/
Muscle Contraction
Limits:
Animals
Language:
En
Journal:
Am J Physiol Regul Integr Comp Physiol
Journal subject:
FISIOLOGIA
Year:
2010
Document type:
Article
Affiliation country:
España